More specifically, the invention relates to a ventilation assembly of the type comprising: a support structure or cowl, in which a main flow opening is constructed and which comprises a plurality of struts which extend near the opening as far as a central support structure, preferably of annular shape; and a motorized ventilator including an electric driving motor which is connected to the central support structure and a fan of the axial type which is connected to the motor and which is mounted for rotation in the main flow opening; the fan comprising a plurality of vanes which extend from a cup-like hub which has an annular side wall and a bottom wall and which defines internally a housing in which the associated motor extends; the hub further having a plurality of internal vanes for the ventilation of the motor which extend from the side wall of that hub.